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|Linux Commands - Administrative Commands|
atThe at command will run a script at a specified time. The command is used by typing “a”t and then the time you want the activity to occur. This will create the at> prompt enabling you to enter the commands you desire to run. When you are done press Control+D.
Here is the basic format for an at command:
at [-c | -k | -s] [-f filename] [-q queuename] [-m] -t time [date] [-l] [-r]
[-c | -k | -s] -- refers to the shell you are using C, Korn or Bourne
You could create a file that would be run by at. For example a bash shell script.
-m send mail to the user when it is complete sent by default with /usr/sbin/sendmail
-d this is an alias for atrm which will delete at jobs
-v shows the time a job will be executed
-c cats job to standard output
-t set a time for job to run ([[CC]YY]MMDDhhmm)
-q queue The a queue is reserved for at and the b queue is reserved for batch. If you add a queue then that queue will increase in niceness, which means it will have less priority.
-V prints version number
Who can use at is controlled by /etc/at.allow and /etc/at.deny
If at.allow exists, only those in allow can use it. If at.deny exists and allow does not then everyone not in deny can use it. If neither exist only root can use it.
MMDDYY, MM/DD/YY, or MM.DD.YY formats
now + time the current time is in minutes, hours, days, or weeks. For example, now + 3 days
atq to view pending jobs
at> touch mkdir test
Unlike cron, these jobs will only run once.
-l list jobs
-d jobnumber delete a job
This example shows that the user root has two jobs waiting.
2 2005-09-11 09:07 a root
at -d 1
This will delete job1.